Energy Considerations for Pet Doors

Keep Fido (or Fluffy) happy without the drafts

By Hannah McKenzie

Q: I am considering installing a cat door so my cat can come and go as she pleases, rather than waking me during the night to go outside. I see several green and energy efficient products online, but I’m suspicious of their claims. How do I choose a good cat door and prevent as much air loss as possible?

A: Interrupted sleep from pets can be annoying, so a quality pet door might be a decent solution that is worth the extra energy lost.

Assuming your ceilings and floors are adequately air‑tight, a tightly closing pet door would not be a huge energy drain. Like a single-pane glass window, it will keep out pests and outdoor air but not likely be an energy efficient feature. For homes with lots of air leaking through the ceilings and floors, a pet door, especially a leaky one, may increase your monthly energy bill and add a noticeable breeze. Pet doors range in quality and price — from $6 to $2,000 — including questionable “green” options, and no consistent testing method exists for identifying the products that best limit air loss.

Location

Pet doors are most often installed in human doors and sometimes through walls. There is not a huge difference with regard to energy. Some people hope that installing two pet doors through a wall will act like double-pane glass, but testing hasn’t shown this to always work. If you are the creative type, an air-lock entry system like you see at hospitals, hotels and grocery stores would limit air loss. This means two entry doors with a foyer space between them or a high-speed fan that blows across the opening to prevent indoor and outdoor air exchange. Perhaps a simpler option is having a pet door lead to your garage or screened porch so Fluffy can roam with safety from coyotes and tomcats.

Design

Select a door design that closes snugly to limit air leaking and rodents or bugs entering. Even better are pet doors with latches or covers for times when you don’t want Fluffy (and air) coming and going as she pleases. Some doors have a computerized latch linked to a microchip under your pet’s skin or on your pet’s collar to prevent other neighborhood critters from coming to visit.

Other considerations

“Greenwashing” (bogus claims about energy savings) is rampant in pet door advertisements. Carefully consider product reviews and be ruthless when analyzing product features. One pet door manufacturer claims that the three inches of air space between its two door flaps provide “heavy-duty insulation.” I beg to differ.

In addition to energy loss, pet doors can create other hassles … or entertaining stories. My neighbor recently found a raccoon helping itself to cat food in her kitchen. The pictures were a hoot (mostly because it wasn’t my kitchen)! Freshly killed game and muddy paws can also make their way inside.

Instead of pet door mishaps, consider pet training books and online videos as other options. If a service animal can open and close doors, maybe your pooch can too. Would an automatic feeder set to 4 a.m. satisfy your frisky alarm clock? Perhaps Smokey learns to use a human toilet and doesn’t wake you for outdoor bathroom breaks? So many possibilities to get more sleep.

About the Author

Hannah McKenzie is a residential building science consultant at Advanced Energy in Raleigh who specializes in working with nonprofit developers like Habitat for Humanity to make new affordable housing energy efficient.

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Comments (1)

We installed a pet-door in the wall between the garage and the laundry room. This is how we use pet doors- The litter box and tracked litter is all in the garage now. Adding a cat door in the garage somewhere to the outside might allow cat to travel from house to closed space to outside? Another option is to put the cat out before bed? Just some thoughts.

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